How To Read Tire | Decode Sidewall Marks

Tire sidewall codes show width, profile, wheel size, load rating, speed symbol, build type, and tire age in one line.

Learning How To Read Tire markings gets a lot easier once you know the order. A sidewall is not random. It’s a compact label that tells you what size the tire is, what wheel it fits, how much weight it can carry, how fast it is rated to run, and when it was made.

If you can read that label, you can shop with less guesswork, spot a mismatch before it causes trouble, and check whether a used tire is even worth your time. You’ll also know which numbers matter for safety and which ones get misread all the time.

What The Main Tire Code Looks Like

Most passenger vehicles use a code that looks close to this: P215/65R16 95H. Each part has a job. Read it from left to right, and the code starts to make sense fast.

• P = passenger tire
• 215 = section width in millimeters
• 65 = aspect ratio, or sidewall height as a percentage of width
• R = radial construction
• 16 = wheel diameter in inches
• 95 = load index
• H = speed rating

Some tires start with LT for light truck, ST for trailer, or T for a temporary spare. That first prefix tells you what sort of job the tire was built for, not just its size.

How To Read Tire Sidewall Codes Step By Step

Start with the first number group, not the brand name or the big treadwear claims. Width comes first. In P215/65R16, the tire is about 215 millimeters wide from sidewall to sidewall.

Next comes the aspect ratio. Here it’s 65, which means the sidewall height is 65% of the tire’s width. A lower number usually means a shorter sidewall and a firmer feel. A taller number usually means more cushion and more sidewall flex.

Then you’ll see a construction letter. On modern road cars, that’s almost always R for radial. After that comes the wheel diameter. A tire marked 16 fits a 16-inch wheel. It will not stretch onto a 17-inch wheel, and a 15-inch wheel will not seat it either.

The last part of the main sequence is the service description. In 95H, the number is the load index and the letter is the speed rating. That pair matters when you replace tires. You don’t want to drop below what your vehicle calls for.

Bridgestone’s tire size guide lays out the same left-to-right order and is handy when you want to double-check an odd marking.

What Load Index And Speed Rating Tell You

The load index is not a weight number by itself. It’s a code that matches a load chart. A higher number means the tire can carry more weight when inflated to the proper pressure. That matters on SUVs, pickups, vans, and any vehicle that sees passengers, cargo, or towing duty.

The speed rating is the letter after the load index. Common ratings include S, T, H, V, and W. It does not tell you what speed you should drive. It tells you the tire’s tested speed capability under set conditions.

If your car came with one rating, don’t swap to a lower one just because the size looks the same. Matching the vehicle placard, owner’s manual, or the tire already specified by the maker keeps the tire package in the zone the car was built around.

Common Prefixes And Extra Marks

You may also spot marks outside the main size line. M+S means the tire is marked for mud and snow. A three-peak mountain snowflake symbol marks a tire that passed a harsher snow-traction test. XL or Extra Load points to a tire built to carry more load at higher inflation pressure than a standard-load version of the same size.

There may also be a rotation arrow, an outside/inside mark on directional or asymmetrical tires, and a UTQG line showing treadwear, traction, and temperature grades. Those marks help, but the size code, load index, speed rating, and date code are the first things most drivers should read.

Sidewall Mark	What It Means	Why It Matters
P	Passenger tire type	Shows the tire’s intended vehicle class
LT	Light truck tire type	Built for heavier duty use and different load demands
215	Width in millimeters	Affects fit, grip, and wheel clearance
65	Aspect ratio	Shows sidewall height compared with width
R	Radial construction	The standard build on most modern vehicles
16	Wheel diameter in inches	Must match the wheel exactly
95	Load index	Shows how much weight one tire can carry at proper inflation
H	Speed rating	Shows the tire’s tested speed capability
DOT	Federal compliance and tire ID sequence	Helps you find plant data and the manufacture date

How To Find The Tire Age From The DOT Code

Look for the letters DOT on the sidewall. Near the end of that sequence, the last four digits show the week and year the tire was made. A code ending in 1324 means the tire was produced in the 13th week of 2024.

That date matters more than many buyers think, especially with used tires, spare tires, trailers, and vehicles that sit for long stretches. A tire can look fine and still be old. Rubber ages from time, heat, sunlight, and storage conditions, not just miles.

NHTSA notes on its TireWise tire safety page that the last four digits of the DOT Tire Identification Number show the week and year of manufacture, and it also points drivers to the door-jamb placard or owner’s manual for the correct tire size and pressure.

Check Both Sides For The Full DOT Line

Some tires show the full DOT sequence, including the date code, on only one sidewall. If you can’t find the last four digits right away, look at the inner sidewall too. That saves a lot of wrong guesses when you inspect a spare or a used set.

Code You See	Read It As	What To Do
1324	13th week of 2024	Check condition, tread depth, and storage history
0321	3rd week of 2021	Fine to inspect, then judge by wear and cracking
4818	48th week of 2018	Inspect with extra care for age-related drying or cracks
DOT on one side only	Full date may be on the other sidewall	Check both sides before buying or fitting

Marks Drivers Mix Up All The Time

A common mistake is using the maximum pressure molded into the tire sidewall as the pressure you should run every day. That is not your go-to inflation target for normal driving. Your vehicle’s door-jamb placard or owner’s manual is the better source for the right cold pressure for that vehicle setup.

Another mix-up is thinking wheel diameter and tire width can slide around freely. They can’t. A tire marked for a 16-inch wheel needs a 16-inch wheel. Width changes can also affect clearance, speedometer reading, ride, and steering feel.

People also confuse load index with ply talk, or assume all-season, mud-and-snow, and severe-snow ratings mean the same thing. They don’t. Read the exact mark on the tire, then match it to the conditions you drive in most.

What To Check Before You Buy Or Replace Tires

Before you order anything, compare five things against the vehicle placard or your current tire if it is the correct factory size:

1. Tire type prefix such as P, LT, ST, or T
2. Width, aspect ratio, and wheel diameter
3. Load index
4. Speed rating
5. DOT date code if you are buying used or old stock tires

Then look at the physical condition. Check for uneven wear, cracking between tread blocks, cuts, bulges, patches, and signs the tire ran underinflated. If the tire has been sitting loose in a shop corner with no known history, be extra picky.

A Fast Way To Practice Reading A Sidewall

Stand by your car and read one tire from left to right. Say the code out loud. Break it into type, width, profile, construction, wheel size, load index, and speed rating. Then find the DOT line and read the last four digits. Do that on all four tires and the spare. You’ll spot mismatches fast.

Once you do it a couple of times, the sidewall stops looking like a jumble. It turns into a label you can use when buying tires, checking a used set, or making sure a tire shop put the right rubber on your wheels.